U.S. Pat. Nos. 6,143,705, 6,310,019, 6,440,856, 6,514,352, 6,514,921, 6,534,458, 6,541,434, 6,716,803, 7,250,391, 7,265,005, 7,312,186, and 7,541,322 discuss various compositions and methods of cleaning semiconductor substrates containing phosphonic acids.
U.S. Pat. Nos. 6,395,693 and 6,541,434 describe a method and composition for cleaning contaminants from the surface of a semiconductor wafer after the semiconductor wafer has been chemically-mechanically polished, the method comprising contacting the surface of the semiconductor wafer having abrasive particle and metal ion contaminants with a composition comprising carboxylic acid is present in an amount of about 2 wt. % or less, said amine-containing compound is present in an amount of about 0.1 wt. % or less, and said phosphonic acid is present in an amount of about, 2 wt. % or less. The cleaning composition desirably has a pH of about 4-6. Preferably, the cleaning composition has a pH of about 4.5-5.5. The weight ratio of phosphonic acid to carboxylic acid is 1:1.
U.S Patent Application No. 20010051597 discusses an aqueous solution of a citric acid concentration of more than 1 vol %, and the chelating, agent is added into the aqueous solution containing the citric acid by 10 ppm or more. The weight ratio of phosphonic acid to carboxylic acid, such is 1:1000 (i.e 10 ppm of phosphonic acid to 1% citric acid)
Phosphonic acid, in particular 1-hydroxyethane 1,1-diphosphonic acid (commonly termed HEDPA) has been in commercial use for many years as a corrosion inhibitor and as a complex agent. It is well understood when HEDPA is used in quantities less than 30 parts to million parts water, it acts as corrosion inhibitor. Above 150 parts to million parts water, it acts as a chelating agent. In the range 30-150 parts HEDPA to one million parts water there is a dead zone; the HEDPA does not perform.
It is known that HEDPA combined with a surfactant produces a synergistic result. The surfactant not only functions as a dispersant but also improves the residue dissolving performance of the HEDPA when the HEDPA is used in strength above 150 parts to million parts water.